var idLargeImage = "top_banner";
var imgLarge;
var numOfImages = 7;	//画像の数
var curNum = 1;
var opacity = 100;
var opaIntIn = 5;	//濃くなる間隔
var opaIntOut = 2;	//薄くなる間隔
var interval = 25;
var si;

function loopPhoto(elm){
	imgLarge = document.getElementById(idLargeImage);
	curNum++;
	if(curNum > numOfImages){
		curNum = 1;
	}
	clearInterval(si);
	si = setInterval(function(){
		fadeOut();
	}, interval);
	
}


function fadeIn(){

	if (opacity >= 100) {
		opacity = 100;
	}

	imgLarge.style.filter = "alpha(opacity:" + opacity + ")";  // IE
	imgLarge.style.opacity = opacity/100;   //Mozilla

	if(opacity === 100){
		clearInterval(si);
		return;
	}
	/*
	if(opacity === 0){
		imgLarge.style.visibility = "visible";
	}
	*/

	opacity += opaIntIn;
}


function fadeOut(){
	
	if (opacity <= 0) {
		opacity = 0;
	}
	
	imgLarge.style.filter = "alpha(opacity:" + opacity + ")";
	imgLarge.style.opacity = opacity/100;

	if (opacity === 0) {
		clearInterval(si);
		//imgLarge.style.visibility = "hidden";
		imgLarge.onload = null;
		imgLarge.src = "";
		imgLarge.onload = function(){
			si = setInterval(function(){
				fadeIn();
				}, interval);
		}
		imgLarge.src = "/top_images/top" + curNum + ".jpg";
	}
	
	opacity -= opaIntOut;


}